Rotary trommel with internal grizzly



June 21, 1955 T. R. CLARK 2,711,250 ROTARY TROMMEL WITH INTERNAL GRIZZLY med Nov. 50, 195s 2 sheets sheet 1 @imdb ATTO R N EYS June 21, 1955 T, R, CLARK v 2,711,250

* ROTARY TROMMEL WITH INTERNAL GRIZZLY Filed NOV. 30, 1,955 2 Sheets-.Sheet 2 "wem-on Thomas R. Cla rk,

, BY I z Z ATTORNEYS Unitel The present invention is directed to, and it is a major object to provide, an improved rotary trommel .adapted for use to effectively classify earth aggregates, especially in connection with mining operations.

In conventional trommels used for this purpose the entire mass of earth aggregates is fed directly onto and moves along the perforate sheet metal cylinder which the trommel includes, any large rocks or boulders in the aggregates running and pounding directly on they sheet metal cylinder, causing damage thereto and its premature deterioration.

It is thus another important object of the invention to provide the trommel with an internal grizzly which functions to effectively segregate the large rocks and boulders from the aggregates, and prevents such rocks and boulders from coming into direct contact with the sheet metal trommel cylinder, so that the latter classifies solely the smaller gangue or gravel, and which does not cause undue wear and tear on said trommel cylinder.

An additional object of this invention is to provide a rotary trommel, as above, wherein the internal grizzly is of open cylindrical configuration, and is composed of a plurality of railroad rails extendinglongitudinally in circumferentially spaced relation; there being a novel mount for ruggedly but removably supporting such railroad rails in a rigid position in the trommel,

A further object of the invention is to provide a trommel with internal grizzly which is not only effective to separate large rocks and boulders from the aggregates before the same reach the perforate sheet metal trommel cylinder, but one whose structure is such that the large rocks and boulders working the aggregates against the rails of the grizzly breaks up all mud or slugs, preventing choking both in the internal grizzly and outer perforate cylinder, whereby to assure of a smoother, more continuous ow in the machine, with greater capacity in yardage.

A separate object of the invention is to provide novel means for producing a constant forward feed of the aggregates in the machine between the internal grizzly and external perforate trommel cylinder.

It is also an object of the invention to provide a rotary trommel with internal grizzly which is of simple but rugged construction, and a machine which functions positively for the intended purpose; i. e., the initial separation of large rocks and boulders from the aggregates, and the subsequent classification of the remainder of the aggregates in the trommel cylinder.

Still another object of the invention is to provide a practical andV reliable rotaryV trommelwith internal grizzly, and one which will be exceedingly effective for the purpose for which it is designed.

These objects are accomplished by means of such structure and relative arrangement of parts as will fully appear by a perusal of the following specification and claims.

In the drawings:

Fig. 1 is a longitudinal sectional elevation of the improved rotary trommel with internal grizzly.

States Patenti() 2,711,250 Patented June 21,1955

Fig. 2 is an end elevation of the same, taken from the discharge end of the machine.

Fig. 3 is a transverse section on line 3-3 of Fig. l.

Fig. 4 is an enlarged fragmentary sectional plan view on line 4-4 of Fig. 2.

rReferring now more particularly to the drawings, and to the characters of reference marked thereon, the machine comprises an elongated rotary trommel, indicated generally at 1, such trommel comprising an external heavy-duty but sheet metal cylinder 2 formed, intermediate its ends, with a multiplicity of perforations 3.

The trommel cylinder 2 is closed at the intake end by anend wall 4; the cylinder extending therefrom at a slight downward incline.

The trommel cylinder 2 is supported, in conventional manner, by rollers 5 carried on beams 6 in a supporting frame which is not otherwise shown; said trommel cylinder 2 being rotated by a ring sprocket 7 to which suitable drive mechanism is connected.

The perforate section of the trommel cylinder 2 terminates short of both the intake and discharge ends of said cylinder, and a concentrating table, indicated generally at 8, is supported-in receiving positiondirectly below said perforate section of the trommel cylinder 1; such concentrating table being of conventional design.

A cylindrical, elongated grizzly, indicated generally at 9, is disposed within the trommel cylinder 2; said grizzly being of substantially lesser diameter than said trommel cylinder, being disposed concentrically therein, and extending from end to end of said trommel cylinder.

At the discharge end of the trommel cylinder `2 the grizzly includes a non-perforate discharge cylinder 10 which is relatively short; the remaining and major portion of the grizzly-i. e. the part of the same between the end Wall 4 and said discharge cylinder 10-being constructed as follows:

Such major portion of the grizzly 9 comprises a plurality of longitudinally extending, circumferentially spaced grizzly bars 11, preferably in the form of railroad rails disposed with their bottom flanges innermost.

The grizzly bars 11 are supported, at longitudinally spaced points in the length thereof, by mounting rings, each of which is indicated at 12; these rings' being slotted, as at 13, in matching relation to the grizzly bars 11, and thelatter projecting through said slots. The slots 13 open to the inner faces of the rings 12, and the bottom or inner flanges of the in-place, railroad rail grizzly bars 11 lie ush with such faces, whereby there is no inward projection to obstruct free movement of the material in the grizzly 9.

The grizzly bars 11 are reieasably s'ecured in position in the rings 12 by L-shaped attachment brackets 14 welded to the ring 12 which is closest to the discharge cylinder 10; suchbrackets 14 being in pairs which lie flush against opposite sides of the web 1S of a projecting portion of each of the grizzly bars 11.

A cross bolt 16 secures each pair of brackets 14 to the corresponding web 15. See Fig. 4. With this arrangement the grizzly bars 11 are normally fixedly secured against displacement from the mounting rings 12, but in the event that replacement of said bars is necessary the cross bolts 16 can be removed and said grizzly bars 11 slid outwardlyk from the rings' 12 through the discharge cylinder 10.

The discharge cylinder 10 is fitted on the outside with longitudinally spaced mounting rings 17, and the latter, together with certain of the mounting rings 12, are attached to the trommel cylinder 2 each by a plurality of circumferentially spaced connector plates 18. These connector plates 18 increase symmetrically in width circumferentially from the grizzly 9 to the trommel cylinder 2, as shown in Figs. 2 and 3, and such plates include arcuate feet 19 fixed to said trommel cylinder, This form of the connector plates 18 enables the same to be set diagonal to the longitudinal axis of rotation; ife., so that they follow a helical path, and said plates are pitched in a direction to cause aggregates in the trommel cylinder 2 to feed :in a direction toward the discharge end thereof.

A relatively large, high pressure, water nozzle V20 is disposed at the discharge end of the trommel cylinder 2, and is set to deliver a stream of water into the grizzly 9 through the discharge cylinder such setting being adjustable by reason of the fact that said nozzlej' is supported by a swivel coupling 2i secured `to the ywater feed pipe 22. p

In operation of the above described rotary trommel with internal grizzly, the earth aggregates are initially delivered into the grizzly 9 adjacent the kend wall 4; this being accomplished by a feed chute or hopper 23 which enters the grizzly 9 through a central port 24 in said end wall 4. After -delivery of the earth aggregates into the grizzly 9, any large rocks or boulders present in such aggregates are retained in the grizzly, working along for the full length thereof, passing finally through the non-perforate discharge cylinder 10 of said grizzly and feeding therefrom to a discharge chute 25.

As the large rocks and boulders traverse the grizzly from end to end thereof they act upon the reminder of the aggregates to break up all slugs or mud which would otherwise cause choking either in the grizzly 9 or trommel cylinder 2; the inwardly exposed bottom or inner anges of the railroad rail grizzly bars 11 providing rugged and effective surfaces on which the aggregates work as the grizzly rotates.

Such remainder of the aggregates as so worked and broken up by the large rocks and boulders in the grizzly 9 deliver downwardly between the grizzly bars 11 and fall into the perforate trommel cylinder 2, wherein further classification occurs; i. e., the lines pass through the perforations 3 and drop into the concentrated table 8, while the gravel and the like flows in said trommel cylinder 2 toward the discharge end thereof, thence feeding into another discharge chute 26.

Flow of the gravel and the like in the trommel cylinder 2, in the direction of the discharge end thereof, is aided and assured by reason of the diagonal setting of the connector plates 18.

It will thus be evident that the large rocks and boulders which in conventional rotary trommels were carried directly on the trommel cylinder 2 are here prevented from gaining access to said trommel cylinder, so that they cannot damage the same; such large rocks and boulders being. confined within the grizzly 9, ultimately feeding to the discharge cylinder 10, and thence delivering therefrom.

In addition to the protection of the trommel cylinder 2 by maintaining the large rocks and boulders out of contact therewith, the action of said rocks and boulders on the remainder of the aggregates in the grizzly is advantageous for the reason that such remainder of the aggregates is pre-worked before entering the trommel cylinder 2 for final classification.

A further advantage is gained from the fact that the weight of the large rocks and boulders is maintained sub stantially centrally within the trommel cylinder 2, with the result that lesser power is required to rotate the cylindrical assembly of the machine.

From the foregoing description it will be readily seen that there has been produced such a device as will substantially fulfill the objects of the invention, as set forth herein.

While this specification sets forth in detail the present and preferred construction of the device, still in practice such deviations from such detail may be resorted to as do not form a departure from the spirit of the inventiom as Y defined by the appended claims.

Having thus described the invention the following claimed as new and useful, and upon which Letters Patent are desired:

l. In a machine for classifying earth aggregates which comprises a generally horizontal rotary trommel cylin-A der, a generally cylindrical grizzly of lesser diameter than the cylinder disposed therein in concentric relation,

the grizzly including a plurality of longitudinal bars arranged in circumferentially spaced relation, and a plurality of longitudinally spaced mounting rings supporting said bars; and disposed with their axes parallelV to the axis of the trommel and means mounting the grizzly in the cylinder for rotation therewith; said means comprising plates extending between the rings and cylinder and'overlappin'g one vertical face of the rings and being secured at their inner end thereto, said plates being relatively narrow at the rings and widening thence to the cylinder whereby the plates may be twisted outwardly of the rings so as to extend in a generally helical path at the cylinder, and being pitched in a direction to cause aggregates in said cylinder to feed toward one end thereof, and means securing the plates at their outer end to the cylinder.

2. In a machine for classifying earth aggregates whichk comprises a generally horizontal rotary trommel Vcylinder, a generally cylindrical grizzly of less diameter than the cylinder disposed therein in concentric relation, `the grizzly including a plurality of longitudinal bars arranged in circumferentially spaced relation, and a plurality of longitudinally spaced mounting rings slotted for recep tion of the bars in slidable and removably iitting relatron, the lbars projecting a relatively short distance beyond one'of the endmost rings, and means to detachably secure the bars to said one endmost ring; such means for each bar comprising brackets secured on the outer face of thering on opposite sides of and adjacent the bar; and a removable bolt extending through thebar andv brackets. Y

3. A structure as in claim 2, in which the bars are of rail form in section and each bar includes a transverse base flange and a radially projecting web disposed centrally of the flange, the base ange being disposed at the radially inner end of the bar and overlying the corresponding brackets, the latter being disposed in adjacent relationship to the web.

References Cited in the tile of this patent y UNITED STATES PATENTS 640,261

Beeman Jan. 2, 1900 796,780 Weaver Aug. 8,1905

883,974 Roughsedge Apr. 7, 1908l 1,343g292 Turner June 15, 1920 2,122,075 Thorold lune 28, 1938 2,664,204 Hurter Dec. 29, 1953 FOREIGN PATENTS Australia June 29, 1935 

